DRAFTINITIAL WATERSHED ASSESSMENT

WATER RESOURCES INVENTORY AREA 12CHAMBERS-CLOVER CREEK WATERSHED

Open-File Report 95-09

Prepared by:

Washington Department of Ecology Southwest Regional OfficeWater Resources Program

P.O. Box 47775Olympia, Washington 98504

Science Applications International Corporation606 Columbia Street NW, Suite 300

Olympia, Washington 98501

Shapiro and Associates1201 Third Avenue, Suite 1700

Seattle, Washington 98101

Taylor Associates722 North 102nd Street

Seattle, Washington 98133

Environmental Systems Research Institute606 Columbia Street NW, Suite 213

Olympia, Washington 98501

March 15, 1995

i

TABLE OF CONTENTS

Page

ABSTRACT.................................................................................................................................... 1

INTRODUCTION........................................................................................................................... 3

WATER DESCRIPTION................................................................................................................ 4GEOGRAPHIC DESCRIPTION ................................................................................................ 4

Subbasins................................................................................................................................. 4Physiography........................................................................................................................... 5

LAND COVER AND LAND USE............................................................................................. 6CLIMATE AND PRECIPITATION TRENDS .......................................................................... 8

Statewide Precipitation Trends................................................................................................ 8Precipitation Trends in the Watershed .................................................................................... 9

HYDROGEOLOGY ..................................................................................................................... 11WATERSHED HYDROLOGY................................................................................................ 11

The Natural Water Balance ................................................................................................... 11The Water Balance as Influenced by Humans ...................................................................... 13

GEOLOGY AND GROUND WATER..................................................................................... 14GROUND-WATER AND SURFACE-WATER INTERACTIONS........................................ 16GROUND-WATER STATUS .................................................................................................. 17

WATER DEMAND ...................................................................................................................... 18WATER RIGHTS AND CLAIMS ........................................................................................... 18WATER QUALITY.................................................................................................................. 22

Surface-Water Quality........................................................................................................... 22Ground-Water Quality........................................................................................................... 24

FISHERIES ............................................................................................................................... 27

STREAMFLOW STATUS ........................................................................................................... 31OBJECTIVES OF ANALYSIS ................................................................................................ 31FLOW EXCEEDENCE ............................................................................................................ 31LOW FLOWS ........................................................................................................................... 32INTERPRETATION OF STREAMFLOW STATUS .............................................................. 33

SUMMARY AND CONCLUSIONS............................................................................................ 34

RECOMMENDATIONS .............................................................................................................. 37

REFERENCES.............................................................................................................................. 39

ii

LIST OF FIGURES

Figure 1. Water Resource Inventory Area (WRIA) Locator Map........................................ 41Figure 2. WRIA 12 – Chambers-Clover Creek Watershed Base Map ................................. 42Figure 3. Precipitation Station Locations ............................................................................. 43Figure 4. Precipitation Trends in Western Washington........................................................ 44Figure 5. Precipitation Contour Map.................................................................................... 45Figure 6. Seattle and Olympia Stations Precipitation Trends............................................... 46Figure 7. Precipitation Measured at McMillin Reservoir – 10-Year Moving Average........ 47Figure 8. The Hydrologic Cycle ........................................................................................... 48Figure 9. Cumulative Growth in Surface-Water Rights ....................................................... 49Figure 10. Cumulative Growth in Ground-Water Rights ....................................................... 50Figure 11. Surface-Water Rights Primary Purpose of Use..................................................... 51Figure 12. Ground-Water Rights Primary Purpose of Use..................................................... 52Figure 13. Impaired Water-Quality 303(d) Listings............................................................... 53Figure 14. Nitrate-Nitrogen Concentrations in Ground Water............................................... 54Figure 15. Salmon and Steelhead Stock Inventory................................................................. 55Figure 16. Flett Creek at Tacoma (USGS Gage 12091100) 1958-1993 Exceedence

Probabilities........................................................................................................... 56Figure 17. Leach Creek at Holding Pond (USGS Gage 12091180) 1966-1990

Exceedence Probabilities....................................................................................... 57Figure 18. Leach Creek Near Fircrest (USGS Gage 12091200) 1956-1934

Exceedence Probabilities....................................................................................... 58Figure 19. Leach Creek Near Steilacoom (USGS Gage 12091300) 1956-1993

Exceedence Probabilities....................................................................................... 59Figure 20. Flett Creek at Tacoma (USGS Gage 12091100) 7-Day Low Flows with

10-Year Moving Average...................................................................................... 60Figure 21. Leach Creek at Holding Pond (USGS Gage 12091180) 7-Day Low

Flows with 10-Year Moving Average................................................................... 61Figure 22. Leach Creek Near Steilacoom (USGS Gage 12091300) 7-Day Low

Flows with 10-Year Moving Average................................................................... 62Figure 23. Leach Creek Near Fircrest (USGS Gage 12091200) 7-Day Low Flows .............. 63

iii

LIST OF TABLES

Table 1. Long-Term Precipitation Stations .............................................................................. 9Table 2. Current Water Right Applications............................................................................ 19Table 3. Water Right Uses and Quantities ............................................................................. 20Table 4. Values Used To Estimate Claims............................................................................. 21Table 5. Water Claims Uses and Amounts............................................................................. 21Table 6. Additional Water-Quality Excursions in Chambers-Clover Creek Watershed........ 25

1

ABSTRACT

The Chambers-Clover Creek Watershed (Water Resource Inventory Area [WRIA] 12) is locatedentirely within Pierce County, Washington between Puget Sound on the west and the communityof Graham on the east. WRIA 12 covers 144 square miles and includes approximately 2k020acres of lakes, extensive wetlands, as well as Chambers Creek and Clover Creek (PCPWU,1994). The watershed is predominantly urbanized, consisting of residential, urban, and lightindustrial uses.

Since 1950, rapid urbanization and suburbanization has resulted in a population of more than267,000 within the Chambers-Clover Creek Watershed. This period of population growth in thewatershed was accompanied by equally rapid expansion of water consumption. Since 1947,combined surface-water and ground-water rights have risen from 91 to 585 cfs (from 12,940 to147,926 acre-ft/year).

Despite closures to further surface-water rights in the major streams, seven-day low flows aswell as summer flows in Flett Creek and Leach Creek, the major tributaries of Chambers Creekhave decreased severely in recent years.

Anadromous fish production in the Chambers-Clover Creek Watershed is relatively low and hasbeen below historic levels for many years. There are many complex and interacting factorswhich are contributing to the low production. Some of these adverse conditions affecting salmonand steelhead include seasonal flooding, low summer flows, unstable stream beds (sedimenttransport), physical barriers, poor water quality, high stream temperatures, the destruction ofspawning habitat, and overharvest of wild stocks.

The interconnection between surface and ground water is apparent in this watershed. Increaseddemands for ground water probably have reduced low flows in the streams. Increases inimpervious surface areas from expanding urbanization have reduced ground-water recharge andhave contributed to reduction of low flows in the drainage basin. The effects of increased waterdemand and reduced ground-water recharge will have even greater consequences during anextended period of below-average precipitation.

The entire are encompassed within the Chambers-Clover Creek Watershed has been designatedby the EPA as part of a Sole Source Aquifer System. This designation is provided to areas inwhich ground water has been identified as serving large populations; over 169,000 people withinthe Chambers-Clover Creek Watershed depend on the Chambers-Clover Creek aquifer as their

2

only source of drinking water (PCPWU, 1994). Despite the need for protection of ground-waterquantity and quality, only limited recent data for static water levels were found. Monitoring ofmany more wells at locations dispersed throughout the Chambers-Clover Creek Watershedwould be required over extended time periods to develop the data necessary for a scientifically-sound, analysis of static-water-level trends.

The National Groundwater Association has classified the uppermost aquifer within the system aseither moderately or highly vulnerable to contamination because of the extremely well-drainedsoils that are common throughout the area (EPA, 1993). The vulnerability has been substantiatedby a number of instances of contamination.

The Clover/Chambers Creek Basin Ground Water Management Program (Brown and Caldwell,1991) suggests a number of control measures to prevent further degradation of the ground waterin the Sole Source Aquifer. These include: underground storage-tank management, cleanup ofhazardous sites, modification of on-site sewage-disposal regulations, development of a well-construction and abandonment program, and maintaining effective solid-waste programs.

3

INTRODUCTION

The Department of Ecology’s Water Resources Program is charged with managing the state’swater resources to ensure that the waters of the state are protected and used for the greatestpublic benefit. An important component of water management relies on permitting andenforcement of water rights, guided by the authority of Chapters 90.03 and 90.44 of the RevisedCode of Washington (RCW). When considering whether to grant a permit for water use, Ecologymust first determine that the proposed water use passes four statutory tests (Chapter 90.03.290RCW):

1. The use will be beneficial.2. The use will be in the public interest.3. The water is physically available.4. The use will not impair senior users.

The axioms of beneficial use and public interest have been defined in regulation. The third andfourth tests comprise a broader test of whether the hydrologic system can perpetually support therequested use along with senior water users. Examples of impairment of older uses includeexcessive reductions of streamflow or lowering of ground-water levels. In practice, water-right-permit decisions often have been made without enough data to adequately predict long-termeffects.

As an efficiency measure and to help make better water management decisions, Ecology intendsto base future allocation decisions on surveys of the hydrologic condition of entire watersheds.

The objective of this report is to document the status of surface-water and ground-waterresources in the Chambers-Clover Creek Watershed, which comprises Water Resource InventoryArea (WRIA) 12. Key water-management issues in the watershed which influence water-rightpermit decisions are identified and documented. Available information was used to assesshydrological, chemical, and biological conditions which broadly indicate the “health” of thewatershed. These conditions included water quantity, hydrogeology, water demand, waterquality, and the status of stocks of resident and anadromous fish species. Assessment of theseconditions was based on readily available information about water rights and claims, streamflow,precipitation, hydrogeology, ground-water levels, fish stocks, and water quality. We did notconduct field surveys or begin data-collection projects. None of this data was exhaustivelychecked for accuracy, given the need for timely completion of the project.

4

WATER DESCRIPTION

GEOGRAPHIC DESCRIPTION

The Chambers-Clover Creek Watershed (Water Resources Inventory Area [WRIA] 12) is locatedentirely in Pierce County, Washington between Puget Sound on the west and the community ofGraham on the east. The waters of Puget Sound off Point Defiance serve as the northern boundaryof the watershed; the City of Dupont is located near the southern boundary. Figure 1 shows thelocation of WRIA 12 in relationship to the State of Washington. The watershed covers 144 squaremiles and includes approximately 2,020 acres of lakes, extensive wetlands, as well as ChambersCreek and Clover Creek (PCPWU, 1994). Elevations within the WRIA start at sea level andextend up to 600 feet. The drainage boundary is defined by topographic highs from which mostrunoff is directed toward the center of the basin (PCPWU, 1994).

The Chambers-Clover Creek drainage originates from spring and ground-water discharge tosprings and seeps in the northeast corner of the watershed. The two most prominent creeks areChambers Creek and Clover Creek. The ground-water discharge forms the headwaters of CloverCreek, which cuts through the center of the watershed, flowing from east to northwest, ending justwest of Interstate 5. Clover Creek enters Steilacoom Lake at river mile (RM) 5.8. ChambersCreek is then formed from the outlet of Steilacoom Lake flowing 4.0 miles north and west down anarrow ravine where it is joined by Flett and Leach Creeks before it discharges to Puget Soundthrough Chambers Bay. The watershed is also typified by a number of small lakes. AmericanLake (the largest lake in the WRIA) is hydrologically linked to ground water and has no naturaloutlet (Figure 2).

Subbasins

Four subbasins are recognized by the Chambers-Clover Creek Watershed ManagementCommittee. Each of the subbasins is equivalent to a smaller watershed. These include: ChambersBay, Clover Creek/Steilacoom Lake, Tacoma West, and American Lake.

The Chambers Bay Subbasin represents 18 percent of the watershed and comprises 17,300 acres.This subbasin includes all drainages downstream of Steilacoom Lake and includes such waterbodies as: Chambers Creek, Flett Creek, Leach Creek, Snake Lake, and Wapato Lake. There is anextensive wetland system within this subbasin associated with Flett and Leach Creeks. The Cityof Tacoma has jurisdiction over a large portion of this subbasin (PCPWU, 1994).

5

The Clover Creek/Steilacoom Lake Subbasin is the largest subbasin in the WRIA and comprises47 percent of the watershed or approximately 45,200 acres. This subbasin includes CloverCreek, Steilacoom Lake, Spanaway Lake, Spanaway Creek, and Morey Creek. There is anextensive wetland system in the area south of Spanaway Lake. McChord Air Force Base and theunincorporated cities of Parkland and Spanaway are included in this subbasin (PCPWU, 1994).

Tacoma West Subbasin is the smallest subbasin within the watershed comprising 8,700 acres or9 percent of the watershed. Most of the water bodies within this subbasin are small streams thatdischarge directly to Puget Sound including Puget Creek, Mason Creek, Day Creek, and NarrowsCreek. This subbasin is dominated by the marine shoreline. Most of this subbasin is within thejurisdiction of the City of Tacoma and the Town of Ruston (PCPWU, 1994).

The American Lake Subbasin represents 25 percent of the watershed (24,200 acres) and isdominated by lakes including American Lake, Gravelly Lake, Lake Louise, and SequalitchewLake. Two creeks within the watershed are Sequalitchew Creek and Murray Creek. There areextensive wetland systems within the subbasin associated with Murray Creek in the area ofDupont. The military installations of Fort Lewis, McChord Air Force Base, and Camp Murraycomprise a substantial amount of land use within the subbasin. (PCPWU, 1994).

Physiography

The Chambers-Clover Creek Watershed lies within the central part of the Puget Sound Lowland,an elongated topographic trough that extends from the Canadian border to the Willamette Valleyin Oregon. The Puget Lowland is bounded on the east by the Cascade Mountains and on the westby the Olympic Mountains and Willapa Hills. Lowland topography is generally flat with almostall of the region lying below 500 feet in altitude (Easterbrook and Rahm, 1970).

The northern part of the lowland was occupied several times by glaciers during the geologicallyrecent periods of glaciation. Thus, most of the topographic features in the Puget Lowland,including the Chambers-Clover Creek Watershed, are a direct result of glacial deposition orerosion (Easterbrook and Rahm, 1970).

Several channels were cut through the area by high-velocity glacial-meltwater streams. Thesechannels often have steep slopes or bluffs defining their boundaries. One of these, the CloverCreek Channel, starts near South Hill on the northeast boundary of the watershed and runssouthwest to the Brookdale and Canyon Road area and into the current floodplain of CloverCreek (PCPWU, 1994). Another, the Kirby Channel, starts just north of Graham on the

6

southeastern border of the watershed and runs through Fredrickson near Canyon Road and 176th

Avenue until it intersects with Clover Creek Channel (PCPWU, 1994). A third, the SouthTacoma Channel, starts near South Tacoma Way and Highway 16 and runs south into theheadwaters area of Flett Creek (PCPWU, 1994).

Elevations within the watershed range from sea level to 600 feet. There are relatively steep bluffsbordering Puget Sound that have steep canyons intersecting them to allow surface-water drainageof the upland areas. The northwestern portion of the watershed, near Fircrest and UniversityPlace, has more steeply rolling hills and valleys which trend in a north-south direction. TheClover Creek floodplain intersects the center of the watershed, flowing from east to west andending just west of Interstate 5. The Chambers Creek canyon is another significant topographicfeature associated with a stream reach. The canyon is two miles long and up to 200 feet deep. Itdrains to Chambers Bay on Puget Sound, on the north edge of the town of Steilacoom (Brownand Caldwell, 1985).

LAND COVER AND LAND USE

The Chambers-Clover Creek Watershed is located entirely in Pierce County. The WRIA ispredominantly urbanized, with land use consisting of residential, urban, and light industrialactivities. Forty-two percent of the land in the watershed is classified as built-up (PCPWU,1994). Large portions (approximately 68%) of the Tacoma West and Clover Creek/SteilacoomLake subbasins are considered urbanized. The Tacoma West Subbasin is distinguished by higherindustrial and higher density commercial land uses, while the Clover Creek/Steilacoom LakeSubbasin is dominated by suburban and medium-density development (PCPWU, 1994).

The least urbanized portion of the Chambers-Clover Creek Watershed is the American LakeSubbasin, particularly within the northern portion of Fort Lewis and along the southwest portionof the subbasin (PCPWU, 1994).

The American Lake Subbasin includes Sequalitchew Lake and Sequalitchew Creek which flowswest into Puget Sound. The development of the Town of DuPont and surface-water usage at theFort Lewis Army Reservation have severely impaired the flow and character of SequalitchewCreek, which has been documented in a report by Andrews and Swint (1994). The 38.4-squaremile drainage basin of Sequalitchew Creek includes Kinsey Marsh which drains into AmericanLake through Murray Creek; seasonal overflow from American Lake flows into SequalitchewLake from which Sequalitchew Creek begins. A Fort Lewis diversion dam, canal, and a set ofcomplicated culverts carry water from the creek into Puget Sound at Tatsolo Point. The

7

remainder of the natural creek flows through Edmond Marsh, a 130-acre wetland bordering FortLewis and DuPont, then through a lush, steep canyon, supplemented by a spring and severalseeps, into a salt marsh, and finally through a culvert under a railroad dike into the Sound.

The original purpose of the Fort Lewis diversion is unclear, and detailed analysis of its effect onflow is difficult because of the lack of data on stream flows before construction of the diversiondam and canal. Controversy remains regarding authorization of the diversion, its effect on thesalmon fishery, and current authority and responsibility for the dam’s operation.

A development (Northwest Landing) is adding another 15,000 residents and additionalcommercial and industrial development along the banks of the creek. The development is onproperty originally owned by E.I. DuPont de Nemours Company, which manufacturedexplosives here for about 75 years. Over 800 acres of the property was contaminated witharsenic, mercury, cadmium, and lead. The DuPont Company and Weyerhaeuser, the current landowner, have completed the remedial investigation and are cleaning up the contaminated areas. Inaddition, a large gravel mine is approved for 360 acres lying north of Sequalitchew Creek andone-half mile from the boundary of the Nisqually National Wildlife Refuge.

Agricultural land includes active and open agriculture. Less than 300 acres (0.3 % of thewatershed) are classified as agricultural. Small farms in the area were not included in thisclassification estimate, but typically support livestock (PCPWU, 1994).

Natural cover accounts for 36 percent of the watershed and includes primarily grasses, shrubs,and brush, but schools, golf courses, cemeteries, landfills, and small farms also were included inthis classification scheme (PCPWU, 1994). The Clover Creek Subbasin supports approximately19,000 acres of natural habitat or 43 percent of the subbasin. The American Lake Subbasin is 38percent natural cover, or approximately 6,500 acres, much of which lies within Fort Lewis(PCPWU, 1994).

The population of Pierce County increased by 112.5 percent from 1950 to 1990. Between 1980and 1990, the population of the county increased 20.7 percent. Population growth historicallyspreads from city centers outward to rural areas. The majority of the population growth duringthe 1980s occurred in the unincorporated areas of the county. Thus, population dynamics haveaffected land use within the watershed substantially.

The 1990 census population within the Chambers-Clover Creek Watershed was 267,344(PCPWU, 1994). A portion of the population of Tacoma (176,664) is included in the WRIA. The

8

incorporated jurisdictions in the WRIA include Steilacoom, Ruston, University Place, Dupont,and Fircrest. Other unincorporated communities include Lakewood, Spanaway, and Parkland.The most extensive development has occurred along the Interstate 5 corridor, especially fromTacoma south to Highway 512 and east to Highway 7.

CLIMATE AND PRECIPITATION TRENDS

Precipitation, either in the form of rain or snow, is the principle source of recharge to the watersupply in the Chambers-Clover Creek Watershed. No weather stations are located within WRIA12, however, based on gages in the vicinity, precipitation in the study area is fairly uniformlydistributed, with slightly increasing precipitation toward the south end. Near Tacoma, at thenorthern boundary of the watershed, annual precipitation averaged 39.4 inches per year from1884 to 1961. The average annual precipitation is 51.6 inches at the Olympia Station which isapproximately 15 miles south of the Chambers-Clover Creek Watershed. Much of theprecipitation in WRIA 12 is lost to evapotranspiration (up to 26 inches per year according toBrown and Caldwell [1985]). Precipitation also enters surface-water drainages and rechargesground water. Most of the ground water eventually discharges as spring flow or direct seepageinto surface water that eventually flows into the Puget Sound.

Statewide Precipitation Trends

Precipitation data from gages located throughout Western Washington were used to examinelong-term trends and identify extended periods of above-average or below-average precipitation.This analysis places the more recent weather patterns into a long-term perspective. Such aperspective is necessary when considering the issuance of additional water rights because periodsof extended drought identified in the historical record can be expected to occur again.

Precipitation stations located at eight sites throughout Western Washington were used for theanalysis (Figure 3). The criteria used to select a particular station were that the record should berelatively long (80 years or more), have few periods of missing data, and be geographicallydispersed from the other stations. Periods of missing data were filled using nearby stations, ifavailable, or by at-station monthly mean values if data from a secondary station were notavailable. Table 1 lists the stations used in the analysis for Western Washington.

The data for the stations were normalized by dividing the annual deviation from the mean by theat-site mean annual precipitation. The normalized data from Stations 1 through 8 in WesternWashington were then averaged to obtain a trend line for each region (Figure 4). In Western

9

Table 1. Long-Term Precipitation Stations

Name County Period of Record

Mean AnnualPrecipitation

(inches)

1. Port Angeles Clallam 1878-1992 25.5

2. Olympia Thurston 1878-1992 51.6

3. Vancouver Clark 1899-1992 38.7

4. Sedro Woolley Skagit 1897-1992 45.9

5. Cedar Lake King 1903-1992 102.7

6. Seattle King 1878-1992 35.5

7. Aberdeen Grays Harbor 1891-1992 82.5

8. Centralia Lewis 1892-1992 45.6

Washington, high variability can be seen throughout the period of record. Since the mid-1950s,the precipitation typically has exceeded the long-term mean. Extended periods of below-averageprecipitation occurred in the 1920s and 1930s and again in the late 1940s. Figure 4 also indicatesthat precipitation in Western Washington was less than average between approximately 1920 and1950 and higher than average between 1950 and 1980. The Western Washington trends indicatea recent decline in average precipitation.

Precipitation Trends in the Watershed

Precipitation contours for the watershed are presented in Figure 3. The Chambers-Clover CreekWatershed is located between the Seattle and the Olympia Stations. The deviations of the annualprecipitation totals from the means for these two stations are shown in Figure 6. The trend lineon the graph is a moving average of the previous 10 years. The trend line indicates thatprecipitation was less than average between 1910 and 1953 and higher than average between1970 and 1992 at the Seattle Station. At the Olympia Station, 15 miles farther southwest and outof the rain shadow of the Olympic Mountains, precipitation fluctuated more around the average.The 10-year moving average was less than the mean between 1920 and 1935, and three periodssince that time. From 1980 until 1993, the 10-year moving average has also been less than themean. In 1993, the moving average was its lowest since 1933. The Western Washington trendsindicating a recent decline in average precipitation were evidenced at the Olympia Station butnot at the Seattle Station.

10

Precipitation data from McMillin Reservoir, located approximately 4 miles northeast of thewatershed, were also evaluated to determine if long-term trends in annual rainfall amounts wheresimilar to other locations in Western Washington. Based on a period of record from 1942-1991,mean annual precipitation at McMillin Reservoir is 40.8 inches. Annual deviations from themean demonstrate high variability in rainfall from year to year (Figure 7). The general trends inprecipitation at McMillin Reservoir, as indicated by a ten-year moving average, has been typicalof the trends observed at other rain gages in Western Washington (Barker, 1995).

11

HYDROGEOLOGY

WATERSHED HYDROLOGY

The hydrologic cycle describes the way that water circulates between the earth and atmosphere.In the cycle, water evaporates from the land and the surface water and is deposited back on landas precipitation, either rain or snow. A portion of the precipitation transpires from vegetation,some infiltrates into the soil, and some runs off into streams. The infiltrating water becomes soilmoisture, some of which percolates to the saturated zone where it becomes ground water.Ground water then flows downward and laterally to discharge through springs and seeps intostreams (Figure 8).

The hydrologic cycle of a watershed matches the global cycle, except that watersheds havedistinct topographic boundaries and consumptive water use by humans becomes an importantfactor. Thus, the six dominant features of a watershed'’ hydrologic cycles are:

1. Precipitation2. Evapotranspiration (evaporation plus transpiration from vegetation)3. Streamflow4. Long-term changes in ground water storage5. Natural ground water flow between adjoining watersheds (under topographic

boundaries)6. Consumptive water use by humans

The Natural Water Balance

The long-term, sustained water balance under “natural” conditions may be written as:

PRE - ET + XAW + CGWS = NSF Equation 1

where “PRE” represents precipitation, “ET” represents evapotranspiration, “XAW” representsground-water exchange with adjacent watersheds, “CGWS” represents change in ground-waterstorage, and “NSF” represents natural streamflow (Figure 6). All terms represent average annualvalues for the purposes of this discussion but could apply to other statistical measures anddurations.

12

Precipitation (PRE) on the watershed is the principal source of replenishment to the water supplyof most watersheds.

Evapotranspiration (ET) consists of evaporation from soils, vegetation, lakes, and streams, inaddition to transpiration by plants. Evapotranspiration reduces the amount of precipitation whichreaches aquifers and streams and constitutes a large percentage of the water balance for mostwatersheds.

Natural ground-water exchange with adjacent watersheds (XAW) may add to or reduce the watersupply of a watershed. In Western Washington, natural ground-water exchange betweenwatersheds often represents only a small portion of a watershed’s total water supply.

Ground-water storage (GWS) is recharged either by precipitation which percolates down to thewater table or by infiltration from streams or other surface water bodies. In the natural cycle,ground water eventually discharges to surface water bodies, except where intercepted by plantsor humans. In a few very deep aquifers, ground water may be relatively stagnant. Rates ofground-water recharge vary with annual and seasonal precipitation. Barring long-term climaticchange or human water use, ground-water storage usually stays within a narrow range, and theaverage recharge to an aquifer is equivalent in volume to the average discharge from the aquiferto streams or other surface water bodies. Thus, barring long-term climate change or excessivewater use by humans, “CGWS” equals zero.

Natural streamflow (NSF) consists of the flow remaining after natural upstream gains and losses.We cannot accurately estimate natural streamflow in most watersheds because streamflowsgenerally were not measured prior to land clearing and development of water supplies.

Simple calculations of the soil-water-balance, based on the method of Thornthwaite and Mather(1948), yield average monthly amounts for precipitation, actual ET, and excess soil moisture.Precipitation is more abundant in fall and winter when vegetation requires less water. As soilsbecome saturated, excess soil moisture percolates beyond the reach of plant roots to rechargeground water. During spring and summer, ground-water recharge practically ceases when therate of ET exceeds precipitation. These alternating cycles are reflected in the low and highseasonal flows in the streams.

Annual ET losses are roughly one half of the annual precipitation. The remainder is available forstreamflow and ground-water recharge. More than 80 percent of the annual precipitation fallsbetween October and April, with much of it running off in streams a short while later.

13

Very little ground-water recharge occurs from May through September, and water levels declineas some of the water drains to streams. These seasonal imbalances lead to large seasonal swingsin streamflow and ground-water storage.

The Water Balance as Influenced by Humans

Given the mandate to protect senior water rights, instream baseflows, water quality, and ground-water levels, all of the naturally occurring water in a watershed is not available for allocation.This leads to another equation defining the available water supply for human use.

NSF – ISF = ASF Equation 2,

“NSF” represents natural streamflow. “ISF” represents in-stream flow (also called base flow)which is reserved for instream needs. Instream flow is intended to serve navigation, recreation,aquatic and riparian ecosystems, fish, wildlife, and esthetics. “ASF” represents availablestreamflow, assuming no water use by humans.

Consumptive water use (CWU), due to diversions of surface water and pumping of groundwater, reduces the available streamflow (ASF). Consumptive water use refers to that portion ofthe diverted or pumped water which is removed from the watershed – usually by increasingevapotranspiration (ET), or by exporting water to other watersheds through canals or pipes. Theremainder of the water returns to the water supply, though often in a different part of thewatershed. It may return by percolation to ground water and, thence, to streams, or it may returnby direct discharge from a pipe. This can be represented as:

WD - RTF = CWU Equation 3

where “WD” represents water diverted (surface water or ground water) and “RTF” representsreturn flow to the stream.

Adding Equations 2 and 3 yields:NSF - ISF - CWU = RASF Equation 4

where “RSF” represents remaining streamflow. After satisfying senior water rights (CWU) andin-stream flow rights (ISF), the remaining available streamflow (RASF) may be available forappropriation (Equation 4).

14

The above water-budget equations serve only to illustrate the major components of thehydrologic cycle in WRIA 12. Unfortunately, the equations are too simplistic to use inaccurately deriving the available water supply. The complex changes (monthly, seasonal, andannual) in all the components, as well as in the factors influencing them, must be measuredand interpreted statistically before reasonably accurate estimates of water availability can bemade. Such is not within the scope of this initial watershed assessment.

GEOLOGY AND GROUND WATER

The Clover-Chambers Creek Watershed is comprised of a broad, poorly drained upland driftplain ranging in altitude from sea level to 600 feet. The drift plain was deposited by glaciers andstreams and is composed primarily of thick sequences of low-permeability glacial tills, andhigher permeability outwash deposits. Volcanic and sedimentary rocks of Tertiary age underliethe entire watershed, but are deeply buried by the unconsolidated glacial and fluvial sediments.The nearest consolidated rock or bedrock exposures occur about 4 miles east of the study areanear the Puyallup River. The deepest wells in the study area (over 2,000 ft deep) did notencounter bedrock (Walters and Kimmel, 1968).

Un-lithified deposits in the Chambers-Clover Creek Watershed can be divided into two majorcategories based on the environment of deposition and hydrogeologic characteristics. Onecategory consists of sediments deposited as a result of glacial activity. The second categorycontains non-glacial sediments deposited between periods of glaciation. These materials are alsobeing deposited today in the form of fine-grained bottom sediments in the Puget Sound,floodplain sediments in stream valleys, and organic clays in lakes and bogs. Generally, the non-glacial deposits are more finely grained than the glacial deposits, and, as a result, are of lowerpermeability.

During the Pleistocene Epoch (approximately 1.6 million to 10 thousand years ago), Cordilleranglaciers advanced into the Puget Sound lowland, and then retreated out of the area several times.Thousands of years elapsed between each of the advances; and glaciers varied in thickness andextent. The most recent of these glaciers (Vashon) was approximately one mile thick in thevicinity of Seattle in the Puget Sound lowland. Each of the glaciers deposited a variety of till andoutwash. The outwash is further divided into advance and recessional deposits.

15

Advance outwash, consisting of sand and gravel, was deposited by meltwater streams in frontand along the margins of the glaciers during the advance of the glaciers into the area.Advance outwash consists of poorly sorted mixtures of sands, gravels, and boulders. Thesedeposits are characterized by a tendency for grain sizes to increase toward the top of thedeposit, and they are generally the most permeable deposits found within the study area.Although the advance outwash tends to be coarse grained and permeable, and therefore formsthe major aquifers of the area, these deposits tend to be heterogeneous and areallydiscontinuous.

As the glaciers receded from the Puget Sound, meltwater streams deposited recessionaloutwash, similar in character to the advance outwash, over the compacted till. Recessionaloutwashes tend to have moderate to high permeabilities, making them a good source ofground water. As the glaciers receded from the area, the velocity of the streams was reduced,resulting in finer grained depositions. Recessional outwashes exhibit a tendency to have finergrained sediments near the top of the deposits. The upward fining and the stratigraphicposition relative to the glacial tills can be used to differentiate advance deposits fromrecessional deposits.

Glacial till is a poorly sorted mixture of sediments ranging in size from clay to boulders.Basal till is deposited directly beneath the glacier, and is compacted by the weight of theglacier. Lodgement till, a type formed as ice fragments melt in place, is far less abundantthan basal till and of little consequence for water supplies in the area. Further references totill will be about basal till, only. Generally, tills are too fine grained and compacted to serveas a source of ground water. Instead, tills tend to serve as aquitards, limiting flow of groundwater. However, tills may be absent in localized areas, or may contain courser grainedmaterials. Either of these conditions may result in transport of ground water and potentialcontamination across or below till layers.

Each of the major glaciations that occurred during the Pleistocene created at least one set ofthe advance outwash, till, and recessional outwash. The youngest of these deposits arepresent at, or close to, the land surface, although some deposits may be missing due toerosion. The aquifer system in the Chambers/Clover Creek Watershed consists of alternatinglayers of higher and lower permeability deposits (outwash alternating with till of non-glacialclay and silt). In the Clover/Chambers Creek Basin Ground Water Management Program(Brown and Caldwell, 1991) these layers are denoted as layers A through G. The majoraquifers are the glacially deposited layers A, C, and E. Lower permeability aquitards (B, D,and F) are non-glacial in origin. The uppermost permeable layer (Layer A) was deposited by

16

the Vashon glacier, and is one of the most productive aquifers in the watershed, commonlyreferred to as the shallow aquifer. However, this aquifer'’ unconfined position at the top ofthe stratigraphic column makes it vulnerable to contamination. Another highly productiveaquifer is layer E (termed the deeper aquifer), located beneath several confining (lowpermeability) layers and offering greater protection from contamination.

The depth to ground water in the watershed ranges from 0 to more than 100 feet. The northend of the watershed is characterized by depths to water of greater than 50 feet, while groundwater in the areas of Lakewood and Parkland are generally shallow at less than 20 feet. Mostof the ground water moves to the west toward Puget Sound. However, ground water alongthe northeastern boundary of the watershed flows toward the Puyallup River valley (Brownand Caldwell, 1985).

Ground water within the basin moves relatively rapidly. Velocities are estimated between0.02 and 63 feet per day, although a velocity of 93 feet per day has been reported. Theaverage flow rate is 4.4 feet per day (Brown and Caldwell, 1985).

GROUND-WATER AND SURFACE-WATER INTERACTIONS

Stratigraphic cross-sections in the Clover/Chambers Creek Basin Ground Water ManagementProgram (Brown and Caldwell, 1991) show that the valleys cut by the Clover and ChambersCreeks do not pass through the first confining layer (B) below the Vashon deposits. Thecross-sections also suggest that the confining layers (B, D, and F) are discontinuous, allowingpaths for vertical travel of ground water between aquifers. Whether ground water would flowupward or downward from one aquifer to the next depends on the hydrostatic pressureswithin the aquifers. In general, surface water infiltrates to recharge the upper aquifers, andthese aquifers provide recharge (leakage) to the deeper aquifers in the upper elevations foundin the eastern portion of the watershed. At lower elevations toward the west, the process isreversed; the deep aquifers provide water to the shallower aquifers that discharge to streams.

Depending on the situation, a well pumping from an aquifer near a stream or other surface-water body can either reduce the amount of ground water discharging to the stream orincrease the quantity of water leaking out of the stream. Ground water will discharge tosurface water when the water level in the aquifer is higher than the surface-water level, as isthe case for American Lake which receives much of its water from the hydrologicallyconnected ground water. Conversely, where ground-water levels are lower in elevation than

17

the level in a stream or river, water will flow from the surface water body into the ground,recharging the underlying aquifer.

The interconnection between ground and surface water is evidenced by the relatively highproportion of recharge contributed from stormwater infiltration to ground water (21 percent).Precipitation accounts for 66 percent of the recharge, and septic tank drainage and surface-water bodies account for 11 and 2 percent, respectively (Brown and Caldwell, 1985).

GROUND-WATER STATUS

Because precipitation varies greatly with the season, ground water recharge changesaccordingly. Ground-water levels adjust to the amount of flow into (recharge) and out of(natural discharge or pumping) an aquifer. Thus, ground-water levels change naturally withthe seasons, particularly in the uppermost aquifer which receives the first recharge. Pumpinglowers ground-water levels. If the pumping rates are only a small portion of the flow throughthe aquifer, the water levels may change only slightly and might not be noticed within theseasonal variations of water levels.

Ground water is the dominant source of water supply in the watershed. TheClover/Chambers Creek Basin has been designated as a Sole Source Aquifer by the U.S.Environmental Protection Agency. The aquifer supplies drinking water to more than 167,000people, or approximately 63 percent of the population, within its boundaries. Despite theimportance of ground water within the watershed, Ecology does not maintain a water levelmonitoring network in the Chambers-Clover Creek Watershed, and only limited data forstatic water levels (reported to Ecology) were found. The data were reported on wellsoperated by Parkland Light and Water (1989 to 1994) and Dupont Public Works (1992 to1994). Except for regular seasonal fluctuations in static ground-water levels, no significantincreases or decreases were noted. These data are not sufficient to permit a reliable analysisof water-level trends. Monitoring over an extended period of time at many locationsdispersed throughout the Chambers-Clover Creek Watershed would be required to developthe data necessary for a scientifically-sound analysis of static water-level trends.

In closed-basin lakes in the area, such as American Lake, Gravelly Lake, Lake Louise, SnakeLake, and Wapato Lake, the lake levels reflect ground-water levels in the surrounding area.In the summer of 1994, the level of these lakes declined substantially. Carp Lake, located ahalf mile south of Lake Louise, has been dry for several years.

18

WATER DEMAND

WATER RIGHTS AND CLAIMS

Water-use statistics for the Chambers-Clover Creek Watershed have not been consistentlyrecorded over the years, and an accounting of actual use has never been undertaken. It islikely that illegal water users are using water for irrigation or other purposes; however, it isalso likely that numerous recorded or claimed rights are no longer in use. Although we lackwater-use data and an understanding of actual use, we must assume that all recorded waterrights and claims are fully in use today and represent consumptive water use.

Surface-water use has increased steadily throughout the years (Figure 9), with a total annualwithdrawal of 131 cubic feet per second (cfs) and 2,478 per year acre-feet authorized fromthe surface waters of the watershed. As of September 1994, one application, requesting atotal of 12 cfs for fish propagation was on file at Ecology (Table 2).

Ground-water withdrawals have shown a steady increase (Figure 10), and a total annualwithdrawal of 453.2 cfs (203,401 gallons per minute [gpm]) and 144,705 acre-feet per yearhas been authorized from the watershed. As of September 1994, 17 applications, requesting atotal of 50 cfs (22,395 gpm) for municipal supply, domestic supply, and irrigation were onfile (Table 2).

Surface-water and ground-water rights were sorted by type of use and totaled, and are shownwith instantaneous withdrawals and annual quantities in Table 3. These uses are graphicallydepicted in Figures 11 and 12, with the indicated values representing the primary purposes ofuse, as a percentage of the total allocated Qi. Because only primary purpose of use wasevaluated, some large secondary uses, such as irrigation, were not accounted for. Thesurface-water right issued in 1990 for 96 cfs is a non-consumptive use (for flood control) thatdiverts flow from Leach Creek into culverts in Nalley Valley. This diversion occurs toprevent flooding and is only triggered when Leach Creek flows exceed 60 cfs.

For many water rights, no “Qa” was assigned when the right was granted. This tabulationaccurately reflects paper records, but the total Qa would have been larger if values had beenassigned.

19

To estimate the quantity of consumptive use claimed, an instantaneous quantity (Qi) wasassigned, and an annual quantity (Qa) was calculated to reflect the average withdrawal formost domestic, stockwatering, and incidental uses. The assigned values are listed in Table 4.A conservative instantaneous withdrawal of 1.0 cfs (450 gpm) was assigned to municipal useto allow ease of sorting and to establish an allocation base.

A total of 2,133 claims (221 surface-water claims and 1,912 ground-water claims) were filedin the watershed. Table 5 shows the uses, instantaneous withdrawals, and annual quantitiesassigned to the claims.

Table 2. Current Water Right Applications

SURFACE WATER GROUND WATER

PURPOSE Number Total Qi (cfs) Number Total Qi (cfs)

Multiple Domestic 0 0 9 27.0

Fish Propagation 1 12.0 0 0

Irrigation 0 0 1 0.5

Municipal 0 0 7 22.5

TOTAL 1 12.0 17 50.0

20

Table 3. Water Right Uses and Quantities

SURFACE WATERRIGHTS

GROUND WATERRIGHTS

USE Qi(cfs)

Qa(a-f/y)

Qi(cfs)

Qa(a-f/y)

Commercial/Industrial 10.2 2,519.3 50.0 21,790.1

General Domestic 0 0 0.4 174.5

Multiple Domestic 11.1 0 160.3 61,937.7

Single Domestic 3.7 12.0 9.8 956.7

Environmental Quality 96.0 0 0 0

Fire Protection 2.9 46.0 0 0

Fish Propagation 0 0 4.1 1,741.8

Heat Exchange 0 0 1.0 419.0

Irrigation 7.2 171.3 16.2 2,245.1

Municipal Supply 0 0 207.5 54,432.5

Recreation/Beautification 0 0 0.1 1.0

Stockwatering 0 0 2.1 590.3

Railway 0 0 1.6 405.0

Wildlife Propagation 0 0 0.1 11.5

TOTAL 131.1 2,748.6 453.2 144,705.2

21

Table 4. Values Used To Estimate Claims

USE Qi(instantaneous; cfs)

Qa(annual; gpm)

Domestic 0.02 0.5

Stockwatering 0.02 0.5

Irrigation 0.02 2.0

Municipal 1.0 (not calculated)

Other 0.02 0.5

Table 5. Water Claims Uses and Amounts

SURFACE WATER CLAIMS GROUND WATER CLAIMS

PURPOSE Qi (cfs) Qa (a-f/y) Qi (cfs) Qa (a-f/y)

Domestic Supply 2.0 49.0 30.6 751.5

Stockwatering 0.6 1.5 6.4 160.0

Irrigation 2.5 2,110.0 8.5 2,732.0

MunicipalSupply

0 0 1.0 Not calculated

Other 0.6 14.5 2.2 488.8

TOTAL 5.7 2,167.0 48.7 4,132.3

22

WATER QUALITY

Surface-Water Quality

Water quality is an important measure of a watershed’s overall health and affects the ability oflife to survive and flourish within a watershed. The importance of adequate water quality andquantity within the Chambers-Clover Creek Watershed is reflected in the following statement:

“Water quality is closely tied to water quantity. Water quality is a significant factor inallocation decisions by water purveyors in that water supplies for municipal andindustrial use (e.g., domestic consumption) must be of high quality. At the same time,management of water quality may depend in large part on the availability of largequantities of water to dilute pollutants and maintain proper water temperatures.”

While this statement is taken from the Draft Green-Duwamish Watershed Nonpoint WaterQuality Early-Action Plan (King County, 1989), it is equally applicable to the Chambers-CloverCreek Watershed.

Many factors adversely affect water quality in the watershed. The geology of the watershedallows rapid infiltration and percolation of degraded or contaminated surface waters. Non-pointpollution sources include on-site septic systems and livestock operations, stormwater runoff fromregional industrial and residential development, and changes in land uses and cover. Pointpollution sources include industrial and municipal discharges.

The status of water quality within the Chambers-Clover Creek Watershed is monitored by theDepartment of Ecology (Ecology), public interest groups, local agencies, and occasional researchstudies conducted on the drainage basin’s water bodies. An overall assessment of conditionswithin the Chambers-Clover Creek Watershed shows that water quality is rated as fair toexcellent for all water bodies in the basin. All of the stream segments within the Chambers-Clover Creek Watershed are classified as Class A according to criteria set by the WashingtonAdministrative Code (WAC) 173-201A. Class A streams are of excellent quality and must bemaintained at that quality. There is also a lakes classification which applies to all of the lakeswithin the watershed. The lakes’ standards are closest in stringency to the Class AA(extraordinary quality) standards for streams (PCPWU, 1994). These classifications identify thestandards these water bodies should meet, if the streams and lakes are to continue to supportbeneficial uses such as drinking water, recreational use, etc.

23

The majority of water-quality problems within the Chambers-Clover Creek Watershed appear tooccur in only a few water bodies throughout the basin. According to the 1994 Section 303(d) listsubmitted to EPA, these problems are largely restricted to excursions beyond the Class A criteriafor fecal-coliform bacteria and total phosphorous loading. Chambers Creek was cited with 10excursions beyond the Class A criteria for fecal coliform at Ecology ambient monitoring station12A070 between January 1, 1990 and January 1, 1992. Three lakes within the basin (AmericanLake, Snake Lake, and Steilacoom Lake) were found to have elevated total phosphorous, inaddition to problems associated with toxic blue-green algae blooms which have resulted inanimal poisonings and public-health advisories. Figure 13 depicts the locations of excursionsdescribed in the 303(d) report.

The Clean Water Act Section 305(b) Report (Ecology, 1992) indicated that in 1992, ChambersCreek (stream segment 12-1101) and Clover Creek (segment 12-1115) were impaired forprimary and secondary recreational use due to the presence of fecal-coliform bacteria at elevatedconcentrations. One source of water-quality impairment listed in the report was municipaldischarges.

A total of four individual NPDES permittees discharge to surface water within the watershed.Two of these permittees are municipal dischargers and two are industrial dischargers. Inaddition, eight general NPDES permits are on file along with two general permits for fishhatcheries. One municipality is permitted to discharge treated wastewater to the ground. Theother source of impairment listed in the report was on-site septic systems which may havecontributed to the degradation of American, Louise, and Steilacoom Lakes which were reportedto be impaired for primary contact recreation due to elevated fecal-coliform bacteria.

Water-quality information is also available from the EPA Storet database. The information wasaccessed for Hydrologic Unit Code (HUC) 17110019. HUC 17110019 covers most of thewatershed but also includes areas in WRIA’s 8, 9, and 10. The surface-water-quality data wereaveraged separately from ground-water-quality data. Data from HUC 17110019 indicate thatconcentrations exceeded the water-quality criteria for fecal coliform, dissolved copper, dissolvedlead, and dissolved silver. These are average concentrations and exact locations for theexceedences are not readily accessible. Thus, the data may reflect elevated concentrations inonly small areas or at locations within the HUC but outside the watershed. It would be difficultto use these data to derive statements about the health of the watershed as a whole.

Site-specific surface-water-quality data was obtained from the U.S. Geological Survey NationalWater Information System (NWIS) database. A review of these data for the watershed indicate

24

that the mean dissolved copper concentration exceeded the acute water-quality criterion in FlettCreek at Tacoma and in Leach Creek near Steilacoom. The mean fecal-coliform count exceededthe water-quality criterion at these same stations, as well as in Chambers Creek at Steilacoomand Clover Creek near Tillicum.

The Preliminary Draft Chambers-Clover Creek Watershed Characterization Plan (PCPWU,1994) indicates that water-quality excursions have occurred in water bodies as indicated inTable 6. In addition, elevated concentrations of metals (copper, lead, antimony, cadmium, andsilver) and polycyclic aromatic hydrocarbons were detected in the sediments of American Lake.

Ground-Water Quality

The entire Chambers-Clover Creek Watershed has been designated by the EPA as part of a SoleSource Aquifer System. This designation is provided to areas in which drinking water supplieshave been identified as serving large populations and where alternative drinking water suppliesare scarce. The purpose of the designation is to provide limited federal protection to drinkingwater sources and to identify areas where water quality should be more stringently protected(EPA, 1993). Over 169,000 people or approximately 63 percent of the population within theChambers-Clover Creek Watershed depend on the Chambers-Clover Creek aquifer as their onlysource of drinking water (PCPWU, 1994). The National Groundwater Association classified theuppermost aquifer as either moderately or highly vulnerable to contamination because of theexcessively well drained soils that are common throughout the area (EPA, 1993). Thevulnerability has been substantiated by a number of instances of contamination.

In 1981, the Washington Department of Social and Health Services (DSHS) surveyed the qualityof the ground water in the watershed. The survey reported fecal-coliform bacteria in 29.5percent of the 117 wells sampled. The southeastern portion of the drainage basin exhibited thehighest levels of contamination (Littler, et al. 1981). In the same study, DSHS reported thataverage nitrate-nitrogen concentrations had risen from 0.5 mg/L in the 1960s to 1.6 mg/L in1981. Three organic chemicals (tetrachloroethylene, trichloroethylene, and 1,2-dichloroethylene)were detected at one sampling well south of the intersection of Interstate 5 and Clover Creek.The source of these contaminants was thought to be the former large-scale cleaning practices atMcChord Air Force Base (Littler, et al., 1981).

Nitrate and chloride concentrations are often used as indicators of the general health of groundwater. According to the 1981 DSHS study (Littler, et al., 1981), the naturally occurringconcentration of nitrate-nitrogen in the Clover/Chambers Creek Watershed ground water is

25

Table 6. Additional Water-Quality Excursions in Chambers-Clover Creek Watershed (PCPWU, 1994)

Water Body FecalColiform

DissolvedOxygen

Total DissolvedGases Temperature pH Turbidity Metals

Chambers Creek ● ● ● ●

Clover Creek ● ● ●

North Fork ●

Morey Creek ●

Spanaway Creek ● ●

Sequalitchew Creek ● ●

American Lake ● ● ● ●

Louise Lake ● ●

Steilacoom Lake ● ●

Snake Lake ● ● ● ●

Wapato Lake ● ●

Spanaway Lake ●

Gravelly Lake ●

Waughop Lake ●

26

assumed to be approximately 0.25 mg/L, based on analyses conducted before 1970. Analysesperformed between 1975 and 1982 indicated generally higher concentrations of nitrate, althoughwell below the drinking water standard of 10 mg/L. Roughly one-third of the more recentanalyses indicated nitrate-nitrogen levels greater than or equal to 1.8 mg/L. The highestconcentration measured was 6.1 mg/L in one well (Brown and Caldwell, 1985). Concentrationsof nitrate-nitrogen measured in 1984 and 1985 spanned from 0.10 mg/L to 6.64 mg/L in theshallow aquifer, with an overall mean concentration of 1.8 mg/L. The mean nitrate-nitrogenconcentration in the deep aquifer was 0.8 mg/L. The Brown and Caldwell study concluded thatthere has been little or no general increase in nitrate concentrations in the deep aquifer over thelast two decades (1965-1985) and a moderate increase in the shallow aquifer.

Chloride concentrations have exhibited a similar trend. According to the 1981 DSHS study(Littler et al., 1981), the naturally occurring chloride level in ground water in this watershed isassumed to be approximately 2.5 mg/L. More recent historical analyses (1975-1982) haveshown that chloride concentrations are greater than or equal to 10 mg/L in nearly half of thesamples (Brown and Caldwell, 1985). There was no statistical correlation of nitrate, chloride,and total dissolved solids concentrations in these samples. Analytical data collected in 1984 and1985 showed higher levels of chloride in the shallow aquifer than in the deep aquifer. The meanyear-round concentration of chloride in the shallow aquifer was 8.1 mg/L, and 5.2 mg/L in thedeep aquifer. Concentrations varied over a greater range in the shallow aquifer. The trendtoward higher chloride concentrations in the shallow aquifer, although not statistically proven,indicates greater impairment of the shallow aquifer than to the deeper aquifer from land useactivities (Brown and Caldwell, 1985). Shallow aquifer nitrate and chloride concentrations werefound to have increased most significantly in the Lakewood, Parkland, and Spanaway areas.Chloride increases are not believed to have been caused by saltwater intrusion, but are morelikely the result of the cumulative affects of septic-tank usage and stormwater infiltration.

Nitrate-nitrogen concentrations from public-supply wells are depicted in Figure 13 and providemore recent estimates of the quality of the ground water in the watershed. The highest measurednitrate concentrations from water-supply wells, based on the 1989 Department of Healthdatabase, were used to develop Figure 14. Forty-six of the wells indicated some evidence ofdegradation in water quality, having concentrations between 2 and 6 mg/ of nitrate-nitrogen.Only five of the wells had concentrations greater than 6 mg/L. None of the wells had nitrateconcentrations that exceeded the primary drinking water maximum-contaminant level (MCL) of10 mg/L. No pattern of localized contamination was detectable from the nitrate concentrations.Based on this analysis, the ground-water quality appears to be of drinking water quality, althoughpristine conditions are no longer present.

27

Newer data have recently been collected by Pierce County on ground-water quality. Nitratelevels will be documented in the Central Pierce County Nitrate Study, due to be issued in lateMarch or April 1995, by the Tacoma/Pierce County Health Department, and Robinson andNoble, Inc. Analyses of 34 wells in Pierce County, including bacteria, nitrogen, anions, cations,metals, chlorinated pesticides, and primary inorganics, have recently been completed and areavailable on the Storet database. Results are anticipated to be analyzed and put in report formatlater this year. In addition, Tacoma/Pierce County Health Department maintains water-qualitydata on all new wells constructed in the county, including over 2,000 wells since 1991; as well ason all Group A and Group B public-water-supply systems.

The EPA Storet database was accessed for HUC 17110019 and the average water-quality-parameter concentrations were provided. The average concentrations exceeded the criteriaprovided in the Ground Water Quality Standards (Chapter 173-200 WAC) for arsenic,manganese, and fecal coliform. Because these are average concentrations and exact locations forthe exceedences are not readily accessible, the data may reflect specific locations of elevatedconcentrations or locations outside of the watershed, rather than the health of the watershed as awhole. It is also noteworthy that the ground-water-quality criterion for arsenic is based oncarcinogenic risk and is exceptionally low (0.05 µg/L).

The Clover/Chambers Creek Basin Ground Water Management Program (Brown and Caldwell,1991) suggests a number of control measures to prevent further degradation of the ground waterin the Sole Source Aquifer. These include: underground-storage-tank management, cleanup ofhazardous sites, modification of on-site sewage-disposal regulations, development of a well-construction and abandonment program, and maintaining effective solid-waste programs.

FISHERIES

The status of fish populations is related to water quality, streamflow, and stream-health within awatershed. As stated in the 1994 Draft Tacoma Watershed Action Plan, “Good habitat isnecessary to support both fish and other wildlife. Some organisms, fish in particular, areconsidered sensitive indicators of stream health. If large numbers and species of fish aresuccessfully spawning and rearing within a stream reach, then it is likely that the stream hasconditions that will support other uses.” Ascertaining the status of fish populations within adrainage basin can be a very important and constructive objective of any environmental study, asit can be used as a preliminary measure of a watershed’s health.

28

The Washington Department of Fisheries’ 1975 Catalog of Washington Streams and SalmonUtilization indicates that anadromous salmonids found within the Chambers-Clover CreekWatershed are chinook (Oncorhynchus tshawytscha), coho (O. kisutch), and chum (O. keta)salmon. Steelhead (O. mykiss) and cutthroat trout (O. clarki) are also found throughout theChambers-Clover Creek Watershed (PCPWU, 1994). Adult or juvenile salmon and/or steelheadtrout are present within the basin throughout the entire year.

The salmonid habitats of the Chambers-Clover Creek drainage have been severely degraded byhuman activities. Physical barriers, both anthropogenic and natural, pose a serious problem toanadromous fish movement within the drainage basin. A dam with a spillway and fish ladderforms the head of Chambers Bay approximately 0.75 miles upstream from the BurlingtonNorthern Railroad dike at tidewater. The outlet of Chambers Bay is very narrow and restricteddue to the railroad dike and tracks across the mouth (Williams, et al., 1975). In addition, a fishtrap near the mouth of Chambers Creek and an impassible dam at the outlet of Steilacoom Lake,restrict the passage of anadromous fish species. All salmon and steelhead that enter ChambersCreek have been netted and placed on the upstream side of the fish trap. Because of theblockage problems encountered, the overall habitat available for anadromous salmonidproduction has been limited to 9.0 stream miles in the lower watershed. Despite these limits, thehabitat that is available for spawning salmon in the lower watershed is rated as fair to excellentquality.

Anadromous fish production in the Chambers-Clover Creek Watershed is relatively low and hasbeen below historic levels for many years. Many complex and interacting factors contribute tothe low production. Some of these conditions adversely affecting anadromous salmon andsteelhead include seasonal flooding, low summer flows, unstable stream beds, physical barriers,poor water quality, high stream temperatures, the destruction of spawning habitat, andoverharvest of wild stocks. Low streamflows experienced over a period of several years areparticularly problematic in this watershed.

Adult salmonids migrate upstream through Chambers Creek estuary throughout the year.Although the Pacific salmon species (chinook, chum, and coho) migrate upstream during latesummer, fall, and early winter, steelhead trout migrate in both winter and summer runs. Timingof upstream migration of the Pacific Salmon is largely controlled by rainfall, streamflow, andbarometric pressure. Migrating salmon aggregate near the mouth of Chambers Creek during Julyand August before migrating predominantly between September through January (Wydoski andWhitney, 1979). Downstream migration by juvenile salmon and steelhead primarily occurs inlate winter and early spring. Chum salmon outmigrate beginning in late February and both

29

chinook and coho begin in early April. Outmigration usually lasts through mid-July to earlyAugust for most species.

Two of the most prominent studies regarding the health of fish stocks in Washington State are:1) A paper published in the March-April 1991 issue of Fisheries entitled, “Pacific salmon at thecrossroads: Stocks at risk from California, Oregon, Idaho, and Washington” (Nehlsen et al.,1991) and 2) The “1992 Salmon and Steelhead Stock Inventory” (SASSI) published in March1993. The former paper attempted to assess the future risk of extinction for selected stocks. TheSASSI report examined the current status of salmon and steelhead stocks for Washington State.The American Fisheries Society risk and SASSI depressed status of streams are presentedgraphically for all species in Figure 15.

The primary anadromous species present within the Chambers-Clover Creek system are the cohoand chum salmon. Chambers Creek coho are of a mixed stock with wild and hatcheryproduction and are currently classified as healthy with annual escapements ranging from 287 to5,848 fish (WDFW, 1993). According to the SASSI report, coho spawn in Chambers Creek andall tributaries. Large numbers of adults from Lake Sequalitchew and the Fox Island Net Penstray into Chambers Creek, and hatchery-origin coho are released into the system aboveSteilacoom Lake. The magnitude of genetic effects caused by cross-breeding these hatchery-origin and natural stock is unknown.

Chambers Creek sustains a healthy population of winter-run chum salmon. These fish are of anative stock and are produced by natural or wild production. These fish are produced naturally.Escapement levels for this winter chum stock range from 200 to 6,300 individuals based oninformation from 1968 to 1991. A Washington Department of Fisheries hatchery on ChambersCreek uses the natural spawning chum run as broodstock. Fish from the hatchery are used tomaintain runs in the Puyallup River system (WDFW, 1993). Chambers Creek formerly had anative summer run of chum salmon. Their escapement and number of fish returning to the creekto spawn ranged from 0 to 200 individuals between 1975 and 1980. They spawned from midthrough late October in Chambers and Leach Creeks. The last three fish were seen in October of1983. The stock has been declared extinct (WDFW, 1993; PCPWU, 1994).

The SASSI report (Figure 15) indicates that summer/fall chinook populations within ChambersCreek and other South Sound Tributaries are of a mixed stock and are regarded as healthy.Chinook stocks are of a composite production meaning that stock status depends mainly uponhatchery production, although some sustained natural spawning occurs.

30

Mathews and Olson (1980) studied factors that can affect Puget Sound coho salmon runs. Theyconcluded that summer streamflow was an important determinant of coho run strength since1952, apparently due to its affect on the first year of the salmon’s life. They also referenceearlier studies which indicate a relationship between rearing flows and coho run strengthbeginning in 1935. Mathews and Olson’s report suggests survival of hatchery coho may bedependent upon the same environmental conditions that affect stream-reared coho.

31

STREAMFLOW STATUS

OBJECTIVES OF ANALYSIS

As previously discussed, the demands on surface-water and ground-water use have grownrapidly over the past 20 to 30 years in the Chambers-Clover Creek Watershed. Increasing waterdemands and periodic declines in precipitation can affect the streamflow status, most notably byreducing summer low flows. To better understand the characteristics of the stream systems inthe basin, streamflow and precipitation data from the watershed were analyzed.

Streamflow data from one USGS gage along Flett Creek and three gages along Leach Creekwere evaluated for flow-exceedence statistics and low-flow trends. In the analyses presentedbelow, all available records were used which did not include unusual or atypical flow conditions.The data for Flett Creek at Tacoma (USGS Gage 12091100) were collected from 1958 to 1993.For Leach Creek, data were collected from 1966 to 1990 at Holding Pond (USGS Gage12091180), from 1956 to 1993 near Fircrest (USGS Gage 12091200), and from 1956 to 1993near Steilacoom (USGS Gage 12091300). For each of these gages, summer flow data were notcollected for a number of years since 1986. For the Leach Creek Gage near Fircrest, no summerflow data were collected during May through September from 1987 through 1988. For the LeachCreek gages near Steilacoom and the Holding Pond and for the Flett Creek Gage at Tacoma, nosummer flow data were collected during May through September since 1985. For the Flett CreekGage near Tacoma, no summer data were collected from May through June in 1991, from Junethrough August in 1992, and from June through September in 1993.

Other gage stations exist but did not meet the criteria for analysis because they did not have anadequate period of record or the period of record was interrupted. Gages are located at CloverCreek near Tillicum; on Flett Creek at Mountain View Memorial Park; and on Chambers Creekby Leach Creek near Steilacoom. These gages should be maintained and monitored consistentlyto establish a broader, more representative database of instream flows within the WRIA.

FLOW EXCEEDENCE

Flow-exceedence curves were developed for each of the selected gage stations along Flett Creekand Leach Creek (Figures 16-19). Thirty-five years of flow data for Flett Creek and 24 to 38years (depending on the gage) of flow data for Leach Creek were used in calculating monthly

32

flow curves for 90, 50, and 10 percent exceedence probabilities. The 90-percent curve representslow-flow conditions, since flows at any time during a given year have a 90-percent probability ofexceeding the plotted values. The 50-percent curve shows the median-flow values andapproximates normal flow conditions throughout the year. The 10-percent curve isrepresentative of high flow conditions. Based on the 10-percent exceedence curves, one canconclude that even at the maximum flow neither Flett Creek nor Leach Creek drains vastquantities of water from the basin. The 10-percent exceedences reach approximately 43 cfs forFlett Creek and 27 cfs for Leach Creek.

The gages along Flett Creek and Leach Creek show flow patterns typical for streams in WesternWashington. In general, flow rates are at their lowest level from May through September(Figures 16-19) and reach their highest level in the wet winter months. During summer, lowflows in Flett Creek at Tacoma are about 1 cfs, median flows range from 2-3 cfs, and high flowsare about 5 cfs (Figure 16). During the winter, the difference between low and high flows inFlett Creek can be up to 40 cfs.

Leach Creek gages at Holding Pond and near Fircrest indicated low flows of about 2 cfsthroughout the year (Figures 17 and 18). Median flow values ranged from 2 cfs in the summer to6 cfs in the winter. High flow values ranged from 3 to 5 cfs in the summer to as high as 14 cfs inthe winter.

The gage on Leach Creek near Steilacoom indicated low flows of 6 to 7 cfs, on average,throughout the year (Figure 19). Median flow values ranged from 8 cfs in the summer to 14 cfsin the winter. High flow values ranged from 10 to 12 cfs in the summer to as high as 26 cfs inthe winter.

LOW FLOWS

The flow-exceedence curves presented in Figures 16 through 19 are based on statistics calculatedfor the entire flow record and provide no indication of flow trends over time. To evaluate trendsin flow, low flows were evaluated by calculating the lowest seven-day-mean flow for each year.The seven-day flow duration is conventionally used in evaluating low flows because shorter flowdurations have much greater variability. A ten-year moving average was used to analyze trendsin the data. The ten-year moving average for a given year serves to smooth out annual variationsand is slow to respond to drastic changes from year to year.

33

When plotted over time, the Flett Creek Gage data indicate an increasing trend in the lowestseven-day mean flow (hereinafter, seven-day low flow) each year from 1975 to 1985 (Figure 20).Summer flows, however, have not been recorded since 1986 which precluded analysis of recenttends in seven-day low flow. For several of the summers recorded, seven-day low flows werebelow 0.5 cfs in Flett Creek.

No summer flow data were collected since 1986 for the Leach Creek gages at the Holding Pond(Figure 21) and near Steilacoom (Figure 22) which precluded analysis of recent trends in seven-day low flow. Low flows tended to increase from 1968 through 1982 at the Holding Pond Gageand diminish slightly thereafter. The gage on Leach Creek near Steilacoom showed decreasinglow flows from the 1960s until 1979 and an increase between 1975 and 1986 (Figure 22).

For the Fircrest Gage, flow data were not collected during the summers 1987 and 1988 (Figure23). The ten-year moving average is shown up to 1986 for the Fircrest Gage, where thediscontinuity in summer flow data occurs. Recent seven-day low flows have been about 1 cfssince 1989, which is lower than average in comparison to the full period of record (Figure 23).

INTERPRETATION OF STREAMFLOW STATUS

No minimum instream-flow requirements have been established for this watershed. However,WAC 173-512 (1980) closed Chambers, Clover, and Sequalitchew Creeks, and their tributaries(including lakes) to further water withdrawals.

Because the summer flows have not been measured since 1986 at three of the gages (previouslydiscussed), no conclusions can be drawn about trends in low flows. For the Fircrest Gage onLeach Creek, the recent record indicates below average seven-day low flows.

Increasing demands for surface and ground water can affect low flows. Furthermore, increasesin impervious surface areas due to expanding urbanization reduces ground-water recharge and,thereby would reduce base flows in the drainage basin. The effects of increased water demandsand reduced ground-water recharge will have even greater consequences during an extendedperiod of below-average precipitation.

34

SUMMARY AND CONCLUSIONS

The watershed covers 144 square miles and includes approximately 2,020 acres of lakes,extensive wetlands, as well as Chambers Creek and Clover Creek (PCPWU, 1994). Thewatershed is predominantly urbanized, consisting of residential, urban, and light industrial uses.Forty-two percent of the land in the watershed is classified as built-up (PCPWU, 1994). Sincethe 1950 rapid urbanization and suburbanization (112.5 percent from 1950 to 1990) has resultedin a population of more than 267,000.

The period of population growth in the watershed was accompanied by equally rapid expansionof water consumption. During the period since 1947, combined surface-water and ground-waterrights have risen from 91 to 585 cfs and from 12,940 acre-ft/year to 147,926 acre-ft/year. Afterthe 1980 closure of Chambers, Clover, and Sequalitchew Creeks and their tributaries, the rise inwater consumption has been dominated by the granting of ground-water rights.

The interconnection between surface water and ground water is apparent in this watershed.Increased demands for ground water probably have affected low flows in the streams, althoughnot enough data are available to draw quantitative conclusions. Increases in impervious surfaceareas from expanding urbanization have reduced ground-water recharge and base flow.

Because the summer flows have not been measured since 1986 at three key gages, noconclusions can be drawn about trends in low flows. For the Fircrest Gage on Leach Creek, therecent record indicates below average seven-day low flows.

No minimum instream-flow requirements have been established for this watershed in WAC 173-512. Establishment of minimum flows should be considered for the major stream sin thewatershed. The minimum flows could be based on pre-1980s flow data. Once established,water-conservation and reallocation plans could be implemented to re-establish base flows in thecreeks. Future ground-water withdrawal should be curtailed until the minimum flows are met.To assist in re-establishing flows, a program to account for all water withdrawals (including theexempt withdrawals of less than 5,000 gallons per day) could be established. Unauthorizedwithdrawals also should be eliminated.

Anadromous fish production in the Chambers-Clover Creek Watershed is relatively low and hasbeen below historic levels for many years. Many complex and interacting factors contribute tothe low production, including seasonal flooding, low summer flows, unstable stream beds,

35

physical barriers, poor water quality, high stream temperatures, the destruction of spawninghabitat, and overharvest of wild stocks.

Salmon habitat is limited to 9.0 stream miles in the lower watershed. The outlet of ChambersBay is very narrow and restricted due to the railroad dike and tracks across the mouth (Williams,et al., 1975). A fish trap near the mouth of Chambers Creek and an impassible dam at the outletof Steilacoom Lake, restrict the passage of anadromous fish species. All salmon and steelheadthat enter Chambers Creek have been netted and placed on the upstream side of the fish trap.

Low streamflows and poor water quality experienced over a period of several years have beenparticularly detrimental to fish in this watershed. The summer low flows experienced in Leachand Flett Creeks are not conducive to fish migration and spawning. Chambers Creek used tohave a native summer run of chum salmon which are now extinct (WDFW, 1993; PCPWU,1994). Water-quality excursions for fecal-coliform bacteria and for phosphorus in lakes havealso reduced the quality and productivity of fish habitat.

The entire Chambers-Clover Creek Watershed has been designated by the EPA as part of a SoleSource Aquifer System. Over 169,000 people depend on the Chambers-Clover Creek aquifer astheir only source of drinking water (PCPWU, 1994). Despite the need for protection of ground-water quantity and quality, ground-water levels have not been comprehensively monitored.Long-term monitoring of wells at locations dispersed throughout the Chambers-Clover CreekWatershed would provide the data needed for analysis of water-level and water-quality trends.

The National Groundwater Association has classified the uppermost aquifer within the system aseither moderately or highly vulnerable to contamination because of the excessively well drainedsoils that are common throughout the area (EPA, 1993). The vulnerability has been substantiatedby a number of instances of contamination.

The Clover/Chambers Creek Basin Ground Water Management Program (Brown and Caldwell,1991) suggests a number of control measures to prevent further degradation of the ground waterin the Sole Source Aquifer. These include: underground-storage-tank management, cleanup ofhazardous sites, modification of on-site sewage-disposal regulations, development of a well-construction and abandonment program, and maintaining effective solid-waste programs.

The assessment of water rights and claims in this report does not measure actual water use orverify water rights for a number of reasons. First, unauthorized-water users and claimed rights nolonger exercised prevent correlation between the amount of water being used and the amount

36

which are of water allocated by rights. No procedure is in place to track whether or not waterrights issued in the past are still used. While numerous old water rights are assumed to be nolonger used, unless a relinquishment form is received by Ecology, water rights remain “on thebooks.” Second, most water-right claimants did not specify quantities on their claims; therefore,quantities for claims were estimated for this report. A survey of actual use is critical to propermanagement of the resource. Third, unauthorized withdrawal has been documented but noteliminated. Such water use should be investigated and enforcement action taken, whereappropriate.

Ecology also must manage the water resources of WRIA 12 without information on water use bythe military. Federal government facilities do not need water rights and are not required to reportwater use or consumption to the State of Washington. Thus, McChord Air Force Base and FortLewis operate their own water supplies independent of Washington’s system of watermanagement.

In addition, the Puyallup Tribe has fishing rights within the watershed that are considered to pre-date water rights and claims. In accordance with the Bolt Phase II decision, water quantity andwater quality must be maintained to ensure adequate salmonid habitat. Implementation of thisdecision may require Ecology to consider the tribal fishing rights as the driving factor in waterallocations, as well as issuance of wastewater-discharge permits and non-point-source pollutantcontrols.

The original purpose of the Fort Lewis diversion is unclear, and detailed analysis of its effect onflow is difficult because of the lack of data on stream flows before construction of the diversiondam and canal. Controversy remains regarding authorization of the diversion, its effect on thesalmon fishery, and current authority and responsibility for the dam’s operation.

37

RECOMMENDATIONS

This initial watershed assessment relied on existing information. There are an abundance ofreports on the study area, but there are some areas where data were lacking. The followingrecommendations call for additional information that will be helpful if a more comprehensivewatershed assessment is conducted in the future.

• Salmon resources should be protected by re-establishing adequate instream flows,and re-establishing natural habitat where such habitat has been reduced due to lowbase flow.

• Minimum instream flows should be established, water reallocation programsplanned and implemented, and future water withdrawal curtailed until the pre-1980s minimum flows can be re-established. To assist as part of the re-establishment of minimum flows:

- Actual water use within the basin should be determined through a systemof annual reporting. This activity could allow relinquishment of un-usedrights and improve the technical analyses of water-use effects.

- Unauthorized water withdrawal should be investigated and enforcementaction should be taken to curtail unauthorized use, if determined to be afactor. This action could return water to the system and may improvestreamflow and water-quality conditions locally.

• An active water-monitoring network should be established. This program couldinclude all major users of ground water within the watershed as well asinstallation of monitoring wells. Data gathering should be coordinated to includestatic-water level and water-quality parameters.

• Water-quality data that are gathered for ground and surface water in the basinshould be consolidated into a single database and access provided in a user-friendly electronic format.

• All currently active weather stations and USGS gages should continue to bemonitored and should be properly maintained.

38

• Efforts of the Chambers-Clover Creek Watershed Management Committee, theClover/Chambers Creek Basin ground Water Management Committee, andEcology’s South Puget Sound Water Quality Management Planning should beintegrated to include protection of both ground and surface water within thewatershed. Planning activities should include resolution of water-quality andwater-quantity issues.

39

REFERENCES

Andrews, E. and M. Swint. 1994. A Twentieth Century History of Sequalitchew Creek.October 1994.

Barker, Bruce. 1995. Long-term precipitation trends in Western Washington. Internal technicalmemo. Department of Ecology. Olympia, Washington.

Brown and Caldwell. 1991. Clover/Chambers Creek Basin Ground Water ManagementProgram. Prepared for the Clover/Chambers Creek Basin Ground Water AdvisoryCommittee. December 1985.

Brown and Caldwell. 1985. Clover/Chambers Creek Geohydrologic Study. Prepared for theTacoma-Pierce County Health Department. July 1985.

Easterbrook, D. and D. Rahm. 1970. Landforms of Washington. Western Washington StateCollege. Bellingham, Washington.

Ecology, 1994. 1994 Section 303(d) List, Department of Ecology, Olympia, WA.

Ecology. 1992. 1992 Section 305(b) Report, Washington State Department of Ecology,Olympia, Washington.

EPA. 1993. Support document for Sole Source Aquifer Designation of the Central PierceCounty Aquifer System. U.S. Environmental Protection Agency, Region 10, WaterDivision. Seattle, Washington February 1993.

King County. 1989. Draft Green-Duwamish Watershed Nonpoint Water Quality Early-ActionPlan. Department of Parks, Planning, and Resources, and other members of the Green-Duwamish Watershed Management Committee.

Littler, J. D., T J. Aden, and A. F. Johnson. 1981. Survey of Groundwater and Surface waterQuality for the Chambers Creek/Clover Creek Drainage Basin, Pierce County.Washington Department of Social and Health Services, Health Services Division, WaterSupply and Waste Section. Olympia, Washington.

40

Mathews, S. B. and F. W. Olson. 1980. Factors affecting Puget Sound coho salmon(Oncorhynchus kisutch) runs. Can. J. Fish Aquat. Sci., Vol 37.

Nehlsen, W., J. E. Williams, J. A. Lichatowich. 1991. Pacific salmon at the crossroads: Stocksat risk from California, Oregon, Idaho, and Washington. Fisheries 16(2):4-21.

PCPWU. 1994. Chambers-Clover Creek Watershed Management Committee, Preliminary DraftWatershed Characterization. Pierce County Public Works and Utilities Water ResourcesDivision.

Thornthwaite, C. W., and J. R. Mather. 1957. Instructions and tables for computing potentialevapotranspiration and the water balance. Drexel Institute of Technology, Laboratory ofClimatology. Publications in Climatology, Vol. 10, No. 3.

WDFW. 1993. 1992 Washington State salmon and steelhead stock inventory. WashingtonDepartment of Fisheries, Washington Department of Wildlife, and Western WashingtonTreaty Indian Tribes. Olympia, Washington.

Walters, K. L. and G. E. Kimmel. 1968. Groundwater Occurrence and Stratigraphy ofUnconsolidated deposits, Central Pierce County, Washington: Washington Departmentof Water Resources Water Supply Bulletin 22, Olympia, Washington, 428 p.

Williams, R. W., R. M., Laramie, and J. J. Ames. 1975. A catalog of Washington streams andsalmon utilization. Volume 1, Puget Sound Region. Washington Department ofFisheries, Olympia, Washington.

Wydoski, R. S. and R. R. Whitney. 1979. Inland fishes of Washington. Seattle, WA andLondon. University of Washington Press. 220 p.

41

42

43

44

Figure 4. Precipitation Trends in Western Washington

45

46

Figure 6. Seattle and Olympia Stations Precipitation Trends

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63